U.S. patent application number 11/787721 was filed with the patent office on 2007-11-08 for air-conditioner for vehicle.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Hiroyuki Hayashi.
Application Number | 20070256436 11/787721 |
Document ID | / |
Family ID | 38659983 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070256436 |
Kind Code |
A1 |
Hayashi; Hiroyuki |
November 8, 2007 |
Air-conditioner for vehicle
Abstract
An air-conditioner includes a refrigeration cycle device having
an evaporator for evaporating refrigerant discharged from a
compressor to cool air to be sent into a vehicle compartment. A
controller turns on the compressor when a surface temperature of
the evaporator or a downstream temperature of air at a downstream
side of the evaporator is equal to or larger than a first
predetermined value. The controller turns off the compressor when a
changing rate of the surface temperature or a changing rate of the
downstream temperature is equal to or larger than a second
predetermined value. The controller turns on the compressor again
when the surface temperature or the downstream temperature becomes
equal to or larger than a third predetermined value, which is
larger than the first predetermined value.
Inventors: |
Hayashi; Hiroyuki;
(Obu-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
38659983 |
Appl. No.: |
11/787721 |
Filed: |
April 17, 2007 |
Current U.S.
Class: |
62/161 |
Current CPC
Class: |
B60H 1/321 20130101;
F25B 2500/19 20130101; B60H 2001/3261 20130101; B60H 2001/327
20130101; B60H 1/00735 20130101; F25B 2700/171 20130101; F25B
2600/0251 20130101; F25B 2700/21173 20130101; F25B 49/022 20130101;
B60H 2001/3263 20130101; F25B 2700/2117 20130101 |
Class at
Publication: |
62/161 |
International
Class: |
F25D 29/00 20060101
F25D029/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2006 |
JP |
2006-129456 |
Claims
1. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent into a vehicle compartment; and a controller
for turning on the compressor when a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state, wherein the controller
turns off the compressor when a changing rate of the surface
temperature of the evaporator or a changing rate of the temperature
of air at the downstream side of the evaporator is equal to or
larger than a second predetermined value, and the controller turns
on the compressor again when the surface temperature of the
evaporator or the temperature of air at the downstream side of the
evaporator becomes equal to or larger than a third predetermined
value, which is larger than the first predetermined value.
2. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent to a vehicle compartment; and a controller for
turning on the compressor when a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state, wherein the controller
calculates the surface temperature of the evaporator or the
temperature of air at the downstream side of the evaporator based
on a revolution number of an engine for driving the compressor,
when the controller detects that the revolution number is equal to
or larger than a second predetermined value, and the controller
uses the calculated surface temperature of the evaporator or the
calculated temperature of air at the downstream side of the
evaporator to turn on the compressor.
3. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent to a vehicle compartment; and a controller for
turning on the compressor when a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state, wherein the controller
calculates the surface temperature of the evaporator or the
temperature of air at the downstream side of the evaporator based
on a temperature outside of the vehicle compartment, when the
controller detects that the temperature outside of the vehicle
compartment is equal to or smaller than a second predetermined
value, and the controller uses the calculated surface temperature
of the evaporator or the calculated temperature of air at the
downstream side of the evaporator to turn on the compressor.
4. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent to a vehicle compartment; and a controller for
turning on the compressor when a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state, wherein the controller
calculates the surface temperature of the evaporator or the
temperature of air at the downstream side of the evaporator based
on a voltage applied to a blower for sending air to the evaporator,
when the controller detects that the voltage is equal to or smaller
than a second predetermined value, and the controller uses the
calculated surface temperature of the evaporator or the calculated
temperature of air at the downstream side of the evaporator to turn
on the compressor.
5. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent to a vehicle compartment; and a controller for
turning on the compressor when a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state, wherein the controller
detects at least two conditions among conditions, in which a
revolution number of an engine for driving the compressor is equal
to or larger than a second predetermined value, a temperature
outside of the vehicle compartment is equal to or smaller than a
third predetermined value, and a voltage applied to a blower for
sending air to the evaporator is equal to or smaller than a fourth
predetermined value, the controller calculates each of the surface
temperature of the evaporator and the temperature of air at the
downstream side of the evaporator based on the detected conditions,
and the controller uses a higher temperature between the calculated
surface temperature of the evaporator and the calculated
temperature of air at the downstream side of the evaporator to turn
on the compressor.
6. An air-conditioner for a vehicle, the air-conditioner
comprising: a refrigeration cycle device including an evaporator
for evaporating refrigerant discharged from a compressor so as to
cool air to be sent to a vehicle compartment; and a controller for
turning on the compressor by detecting a surface temperature of the
evaporator or a temperature of air at a downstream side of the
evaporator, wherein the controller detects a freezing condition
predicting a freezing of the evaporator to be generated while the
evaporator is cooled toward a lowest temperature state, and the
controller raises the surface temperature of the evaporator or the
temperature of air at the downstream side of the evaporator to turn
on the compressor, and continues to control the compressor, when
the controller detects the freezing condition.
7. The air-conditioner according to claim 6, wherein the freezing
condition defines that a revolution number of an engine for driving
the compressor is equal to or larger than a predetermined
value.
8. The air-conditioner according to claim 6, wherein the freezing
condition defines that an outside air temperature is equal to or
smaller than a predetermined value.
9. The air-conditioner according to claim 6, wherein the freezing
condition defines that a voltage applied to a blower for sending
air to the evaporator is equal to or smaller than a predetermined
value.
10. The air-conditioner according to claim 6, wherein the
controller is determined to detect the freezing condition, when the
controller detects at least one condition among conditions, in
which a revolution number of an engine for driving the compressor
is equal to or larger than a first predetermined value, an outside
air temperature is equal to or smaller than a second predetermined
value, and a voltage applied to a blower for sending air to the
evaporator is equal to or smaller than a third predetermined
value.
11. The air-conditioner according to claim 6, wherein the
controller detects at least two conditions among conditions, in
which a revolution number of an engine for driving the compressor
is equal to or larger than a first predetermined value, an outside
air temperature is equal to or smaller than a second predetermined
value, and a voltage applied to a blower for sending air to the
evaporator is equal to or smaller than a third predetermined value,
the controller calculates each of the surface temperature of the
evaporator and the temperature of air at the downstream side of the
evaporator based on the detected conditions, and the controller
uses a higher temperature between the calculated surface
temperature of the evaporator and the calculated temperature of air
at the downstream side of the evaporator to turn on the compressor.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2006-129456 filed on May 8, 2006, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an air-conditioner, which
is typically used in a vehicle.
[0004] 2. Description of Related Art
[0005] JP-A-7-246832 discloses an air-conditioner for a vehicle. A
duct sensor detects a temperature of a compressor, or a temperature
of air at a downstream side of an evaporator, and the detected
temperature is defined as a recognition temperature. The
air-conditioner detects the lowest value among the recognition
temperatures, and calculates deviation of the lowest value relative
to a determination temperature for determining a start or stop of
the compressor. When the calculated deviation is equal to or larger
than a predetermined value, the determination temperature is
increased. Thereby, freezing of the evaporator can be reduced.
[0006] After the compressor is stopped, the recognition temperature
detected by the duct sensor continues to decrease to follow an
actual evaporator temperature. As the actual evaporator temperature
becomes lower, the lowest value of the recognition temperatures
becomes lower.
[0007] However, the deviation is calculated only after the lowest
value of the recognition temperatures is detected. Therefore, the
freezing of the evaporator may be generated while the recognition
temperature is decreasing toward the lowest value. That is, the
above-described control is a feedback control, which may not be
able to prevent the freezing of the evaporator.
SUMMARY OF THE INVENTION
[0008] In view of the foregoing and other problems, it is an object
of the present invention to provide an air-conditioner, in which
freezing of an evaporator can be reduced due to a feed-forward
control.
[0009] According to a first example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent into a vehicle compartment. The
controller turns on the compressor when a surface temperature of
the evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state. The controller turns off
the compressor when a changing rate of the surface temperature of
the evaporator or a changing rate of the temperature of air at the
downstream side of the evaporator is equal to or larger than a
second predetermined value. The controller turns on the compressor
again when the surface temperature of the evaporator or the
temperature of air at the downstream side of the evaporator becomes
equal to or larger than a third predetermined value, which is
larger than the first predetermined value.
[0010] According to a second example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent to a vehicle compartment. The
controller turns on the compressor when a surface temperature of
the evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state. The controller calculates
the surface temperature of the evaporator or the temperature of air
at the downstream side of the evaporator based on a revolution
number of an engine for driving the compressor, when the controller
detects that the revolution number is equal to or larger than a
second predetermined value. The controller uses the calculated
surface temperature of the evaporator or the calculated temperature
of air at the downstream side of the evaporator to turn on the
compressor.
[0011] According to a third example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent to a vehicle compartment. The
controller turns on the compressor when a surface temperature of
the evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state. The controller calculates
the surface temperature of the evaporator or the temperature of air
at the downstream side of the evaporator based on a temperature
outside of the vehicle compartment, when the controller detects
that the temperature outside of the vehicle compartment is equal to
or smaller than a second predetermined value. The controller uses
the calculated surface temperature of the evaporator or the
calculated temperature of air at the downstream side of the
evaporator to turn on the compressor.
[0012] According to a fourth example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent to a vehicle compartment. The
controller turns on the compressor when a surface temperature of
the evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state. The controller calculates
the surface temperature of the evaporator or the temperature of air
at the downstream side of the evaporator based on a voltage applied
to a blower for sending air to the evaporator, when the controller
detects that the voltage is equal to or smaller than a second
predetermined value. The controller uses the calculated surface
temperature of the evaporator or the calculated temperature of air
at the downstream side of the evaporator to turn on the
compressor.
[0013] According to a fifth example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent to a vehicle compartment. The
controller turns on the compressor when a surface temperature of
the evaporator or a temperature of air at a downstream side of the
evaporator is equal to or larger than a first predetermined value
while the compressor is in a stop state. The controller detects at
least two conditions among conditions, in which a revolution number
of an engine for driving the compressor is equal to or larger than
a second predetermined value, a temperature outside of the vehicle
compartment is equal to or smaller than a third predetermined
value, and a voltage applied to a blower for sending air to the
evaporator is equal to or smaller than a fourth predetermined
value. The controller calculates each of the surface temperature of
the evaporator and the temperature of air at the downstream side of
the evaporator based on the detected conditions. The controller
uses a higher temperature between the calculated surface
temperature of the evaporator and the calculated temperature of air
at the downstream side of the evaporator to turn on the
compressor.
[0014] According to a sixth example of the present invention, an
air-conditioner for a vehicle includes a refrigeration cycle device
and a controller. The refrigeration cycle device includes an
evaporator for evaporating refrigerant discharged from a compressor
so as to cool air to be sent to a vehicle compartment. The
controller turns on the compressor by detecting a surface
temperature of the evaporator or a temperature of air at a
downstream side of the evaporator. The controller detects a
freezing condition predicting a freezing of the evaporator to be
generated while the evaporator is cooled toward a lowest
temperature state. The controller raises the surface temperature of
the evaporator or the temperature of air at the downstream side of
the evaporator to turn on the compressor, and continues to control
the compressor, when the controller detects the freezing
condition.
[0015] Accordingly, freezing of the evaporator can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0017] FIG. 1 is a schematic diagram showing an air-conditioner
according to a first embodiment of the present invention;
[0018] FIG. 2 is a block diagram showing the air-conditioner;
[0019] FIG. 3A, FIG. 3B and FIG. 3C are graphs showing
relationships between an evaporator surface temperature and a
sensor detection temperature when load of air taken into an
evaporator is relatively low;
[0020] FIG. 4A, FIG. 4B and FIG. 4C are graphs showing
relationships between an evaporator surface temperature and a
sensor detection temperature when load of air taken into an
evaporator is relatively middle;
[0021] FIG. 5A, FIG. 5B and FIG. 5C are graphs showing
relationships between an evaporator surface temperature and a
sensor detection temperature when load of air taken into an
evaporator is relatively high;
[0022] FIG. 6 is a flow chart showing control of a compressor in
the air-conditioner of the first embodiment;
[0023] FIG. 7 is a flow chart showing control of a compressor in an
air-conditioner according to a second embodiment;
[0024] FIG. 8 is a flow chart showing a subroutine A in FIG. 7;
[0025] FIG. 9 is a flow chart showing control of a compressor in an
air-conditioner according to a third embodiment;
[0026] FIG. 10 is a flow chart showing a subroutine B in FIG.
9;
[0027] FIG. 11 is a flow chart showing control of a compressor in
an air-conditioner according to a fourth embodiment;
[0028] FIG. 12 is a flow chart showing a subroutine C in FIG. 11;
and
[0029] FIG. 13 is a flow chart showing control of a compressor in
an air-conditioner according to a fifth embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0030] As shown in FIG. 1, an air-conditioner includes an
air-conditioning unit 1 and a refrigeration cycle device 10, and is
typically used for a vehicle. An evaporator 9 is disposed in the
air-conditioning unit 1. Refrigerant for cooling air sent into a
vehicle compartment flows in the evaporator 9 and the refrigeration
cycle device 10. When the air-conditioning unit 1 is disposed in an
instrument panel at a front part of the vehicle, the
air-conditioning unit 1 is used for conditioning air adjacent to a
front seat in the vehicle compartment. When the air-conditioning
unit 1 is disposed in a trunk or a side-trim at a rear part of the
vehicle, the air-conditioning unit 1 is used for conditioning air
adjacent to a rear seat in the vehicle compartment.
[0031] The air-conditioning unit 1 has a case 2, and the case 2 has
an air passage, through which air is sent toward an occupant in the
vehicle compartment. An intake air switching box 5 is disposed at
an upstream part of the air passage, and includes an inside air
inlet 3 for taking air inside of the vehicle compartment and an
outside air inlet 4 for taking air outside of the vehicle
compartment. A door 6 is rotatably disposed in the intake air
switching box 5. When the door 6 closes the inside air inlet 3, air
is taken into the box 5 through the outside air inlet 4. When the
door 6 closes the outside air inlet 4, air is taken into the box 5
through the inside air inlet 3. The door 6 is driven by a
servomotor 7. An inside air mode and an outside air mode can be
switched by the servomotor 7. In the inside air mode, inside air
inside of the vehicle compartment is introduced into the box 5
through the inside air inlet 3. In the outside air mode, outside
air outside of the vehicle compartment is introduced into the box 5
through the outside air inlet 4.
[0032] A blower 8 is disposed at a downstream side of the box 5,
and sends air toward the vehicle compartment. The blower 8 has a
centrifugal air-sending fan 8a, which is driven by a motor 8b. The
evaporator 9 is disposed at a downstream side of the blower 8, and
cools air flowing in the case 2. The evaporator 9 is a heat
exchanger for cooling air sent by the blower 8.
[0033] The refrigeration cycle device 10 constructs a refrigeration
cycle, in which the evaporator 9, a compressor 11, a condenser 12,
a receiver 13 and a thermal expansion valve 14 (decompressor) are
connected in a loop. Refrigerant circulates from a discharge side
of the compressor 11 into the evaporator 9 through the condenser
12, the receiver 13 and the thermal expansion valve 14.
[0034] The compressor 11 compresses refrigerant to have a
high-temperature and high-pressure. The high-pressure gas
refrigerant is discharged from the compressor 11, and introduced
into the condenser 12. The gas refrigerant exchanges heat with
outside air sent and cooled by an electrical fan 12a. Therefore,
heat is emitted from the gas refrigerant, and the gas refrigerant
is condensed in the condenser 12. Refrigerant passing through the
condenser 12 is separated into a liquid-phase refrigerant and a
gas-phase refrigerant in the receiver 13, and the liquid-phase
refrigerant is stored in the receiver 13.
[0035] High-pressure liquid-phase refrigerant discharged from the
receiver 13 is decompressed by the thermal expansion valve 14 into
a gas-liquid two-phase state. The decompressed low-pressure
refrigerant is evaporated in the evaporator 9, because the
decompressed low-pressure refrigerant absorbs heat from air. Gas
refrigerant evaporated by the evaporator 9 is again taken into the
compressor 11, and compressed by the compressor 11.
[0036] An open degree of the valve 14 is automatically controlled
such that refrigerant at an outlet of the evaporator 9 has a
predetermined superheat degree. The compressor 11, the condenser 12
and the receiver 13 of the refrigeration cycle device 10 are
arranged in an engine compartment (not shown) of the vehicle.
[0037] A heater core 15 is arranged at a downstream side of the
evaporator 9 in the air-conditioning unit 1, and heats air flowing
through the case 2. The heater core 15 is a heat exchanger for
heating air passing through the evaporator 9 by using coolant of a
vehicle engine (not shown) as a heat source. A bypass passage 16 is
arranged adjacent to the heater core 15, and air bypassing the
heater core 15 flows in the bypass passage 16.
[0038] An air-mixing door 17 is rotatably arranged between the
evaporator 9 and the heater core 15. The air-mixing door 17 is
driven by a servomotor 18, and a rotational position and an open
degree of the air-mixing door 17 can be continuously controlled. An
amount of warm air passing through the heater core 15 and an amount
of cool air passing through the bypass passage 16 can be controlled
by the open degree of the air-mixing door 17. Thus, a temperature
of air blown into the vehicle compartment can be controlled.
[0039] A defrost air outlet 19, a face air outlet 20 and a foot air
outlet 21 are arranged at a downstream side of the air passage of
the case 2. Air-conditioning air is blown toward a window of the
vehicle through the defrost air outlet 19. Air-conditioning air is
blown toward an upper body of an occupant through the face air
outlet 20. Air-conditioning air is blown toward foot of an occupant
through the foot air outlet 21.
[0040] A defrost air door 22 is rotatably arranged at an upstream
side of the defrost air outlet 19. A face air door 23 is rotatably
arranged at an upstream side of the face air outlet 20. A foot air
door 24 is rotatably arranged at an upstream side of the foot air
outlet 21. Each of the doors 22, 23, 24 is opened or closed by a
single servomotor 25 through a link mechanism (not shown).
[0041] The compressor 11 is driven when a rotation power is
transmitted from the vehicle engine to the compressor 11 through a
pulley 11a and a belt (not shown). An amount of refrigerant
discharged from the compressor 11 can be continuously controlled in
response to a control signal output from outside, because a
capacity-variable compressor is used as the compressor 11. The
compressor 11 includes a control valve 110 for controlling its
capacity. Specifically, the compressor 11 has a swash plate, and a
pressure in a swash plate room is controlled by using refrigerant
discharge pressure and refrigerant suck pressure. Thereby, piston
stroke can be controlled by a gradient angle of the swash plate.
Thus, capacity for discharging refrigerant from the compressor 11
can be continuously controlled in a range approximately between 0%
and 100%.
[0042] Next, an air-conditioning electric control unit (ECU) 28
will be described with reference to FIG. 2. The ECU 28 is an
electrical controller of the air-conditioner, and includes a known
microcomputer having a CPU, ROM and RAM, and peripheral circuitry.
The ROM has a control program for controlling air-conditioning
operation, and the ECU 28 performs a variety of calculations and
treatments.
[0043] Sensor detection signals output from sensors 26, and
operation signals output from an air-conditioning panel 27 are
input into an input side of the ECU 28. The sensors 26 are
constructed with an evaporator temperature sensor 26a, an outside
air temperature sensor 26b, an inside air temperature sensor 26c, a
solar radiation sensor 26d and a coolant temperature sensor 26e.
The evaporator temperature sensor 26a detects an evaporator surface
temperature Te of the evaporator 9. The outside air temperature
sensor 26b detects an outside air temperature Tam. The inside air
temperature sensor 26c detects an inside air temperature Tr. The
solar radiation sensor 26d detects a solar radiation amount Ts. The
coolant temperature sensor 26e detects a coolant temperature Tw.
Further, an evaporator downstream temperature sensor (not shown) is
disposed at an air-emitting part of the evaporator 9, and detects a
temperature of air at a downstream side of the evaporator 9. A
sensor signal output from this evaporator downstream temperature
sensor is also input into the ECU 28.
[0044] The air-conditioning panel 27 is arranged adjacent to an
instrument panel (not shown) in front of a driver seat in the
vehicle compartment. Switches 27a, 27b, 27c, 27d and 27e are
provided in the air-conditioning panel 27, and operated by an
occupant, e.g., driver. A target temperature of the vehicle
compartment is set through the temperature switch 27a, and the
temperature switch 27a outputs a signal of the target temperature
into the ECU 28. An inlet mode by the door 6 (the inside air inlet
3 or the outside air inlet 4) is switched by the inlet switch 27b,
and the inlet switch 27b outputs a signal for changing the inlet
mode into the ECU 28. An air-blowing mode is switched by the
air-blowing mode switch 27c, and the air-blowing mode switch 27c
outputs a signal for setting a face mode, bi-level mode, foot mode,
foot defrost mode or defrost mode as the air-blowing mode. An
amount of air sent by the blower 8 is controlled through the air
amount switch 27d, and the air amount switch 27d outputs a signal
for setting the amount of air sent by the blower 8. Further, the
blower 8 is turned on or off through the air amount switch 27d. The
air-conditioning switch 27e is used for turning on or off the
compressor 11. When the air-conditioning switch 27e is turned off,
a control current In supplied to the control valve 110 of the
compressor 11 is forcibly made zero. Thus, the discharge capacity
of the compressor 11 is made approximately zero, and the compressor
11 is in a stop state. When the air-conditioning switch 27e is
turned on, the control current In having a predetermined value
calculated by the ECU 28 is output into the control valve 110 of
the compressor 11.
[0045] The control valve 110 of the compressor 11 controls the
discharge capacity of the compressor 11, and has an electromagnetic
coil 112a. The electromagnetic coil 112a, the servomotors 7, 18, 25
and the motor 8b are connected to an output side of the ECU 28, and
controlled by output signals output from the ECU 28.
[0046] Next, operation of the air-conditioner will be described.
When the air amount switch 27d of the air-conditioning panel 27 is
turned on, the blower 8 starts to operate and sends air in the
air-conditioning unit 1. Then, when the air-conditioning switch 27e
is turned on, the control current In having the predetermined value
calculated by the ECU 28 is output into the control valve 110 of
the compressor 11. The vehicle engine drives the compressor 11 to
have a predetermined discharge capacity. That is, the compressor 11
is in an operation state.
[0047] Thereby, refrigerant circulates in the evaporator 9 of the
refrigeration cycle device 10, and air in the air-conditioning unit
1 is cooled and dehumidified by the evaporator 9. Thus,
air-conditioning air can be emitted into the vehicle
compartment.
[0048] The ECU 28 controls the discharge capacity of the compressor
11. After detection signals output from the sensors 26, and
operation signals input into the air-conditioning panel 27 are
input into the ECU 28, the ECU 28 calculates a target temperature
TAO of air blown into the vehicle compartment. An occupant sets a
target temperature Tset of the vehicle compartment through the
temperature switch 27a of the air-conditioning panel 27. The target
temperature TAO is a temperature of air blown into the vehicle
compartment in order to keep the vehicle compartment to have the
target temperature Tset, even if heat load fluctuates. The target
temperature TAO of air blown into the vehicle compartment is
calculated based on the target temperature Tset of the vehicle
compartment, the outside air temperature Tam, the inside air
temperature Tr, and the solar radiation amount Ts.
[0049] Further, the ECU 28 calculates a target temperature of air
blown from the evaporator 9, and calculates the control current In
to control the capacity of the compressor 11. An actual temperature
of air at a downstream side of the evaporator 9 is detected by the
above-described evaporator downstream temperature sensor for
detecting the temperature of air at the downstream side of the
evaporator 9. The control current In is basically determined such
that the actual temperature of air at the downstream side of the
evaporator 9 becomes approximately equal to the target temperature
of air blown from the evaporator 9. Then, the control current In is
output into the coil 112a of the valve 110, and the capacity of the
compressor 11 starts to be controlled.
[0050] Next, a relationship between an evaporator surface
temperature and a sensor detection temperature of the evaporator
surface temperature, which is detected by the sensor 26a, will be
described with reference to FIGS. 3A-5C, when the compressor 11 is
turned on or off. In FIGS. 3A-5C, nine conditions are selected from
various operation conditions, and a response delay of the sensor
detection temperature relative to the evaporator surface
temperature, temperature changing rates of the sensor detection
temperature and the evaporator surface temperature, and a
temperature difference between the sensor detection temperature and
the evaporator surface temperature are shown.
[0051] The sensor detection temperature is an evaporator surface
temperature detected by the evaporator temperature sensor 26a. Data
of the evaporator surface temperature are sampled at least three or
four times, and the temperature changing rate of the evaporator
surface temperature is calculated by averaging the data. The
temperature changing rate represents a temperature variation per
unit time. That is, the temperature changing rate is a gradient of
a graph of the temperature. A double-chained line in FIGS. 3A-5C
represents a timing for turning on or off the compressor 11. A
dashed line in FIGS. 3A-5C represents the evaporator surface
temperature, and a solid line in FIGS. 3A-5C represents the sensor
detection temperature. Freezing of the evaporator 9 is generated in
an area A, B and C of FIGS. 3A-5C.
[0052] In FIGS. 3A-3C, load of air taken into the evaporator 9 is
relatively low, and a voltage applied to the blower 8 is different.
As shown in FIG. 3A, the sensor detection temperature has the
changing rate of 0.6.degree. C./sec, and the evaporator surface
temperature and the sensor detection temperature have a temperature
difference of 3.0.degree. C. at the maximum. As shown in FIG. 3B,
the sensor detection temperature has the changing rate of
0.6.degree. C./sec, and the evaporator surface temperature and the
sensor detection temperature have the temperature difference of
4.0.degree. C. at the maximum. As shown in FIG. 3C, the sensor
detection temperature has the changing rate of 0.6.degree. C./sec,
and the evaporator surface temperature and the sensor detection
temperature have the temperature difference of 4.8.degree. C. at
the maximum.
[0053] In FIGS. 4A-4C, load of air taken into the evaporator 9 is
relatively middle, and a voltage applied to the blower 8 is
different. As shown in FIG. 4A, the sensor detection temperature
has the changing rate of 0.7.degree. C./sec, and the evaporator
surface temperature and the sensor detection temperature have the
temperature difference of 3.7.degree. C. at the maximum. As shown
in FIG. 4B, the sensor detection temperature has the changing rate
of 0.8.degree. C./sec, and the evaporator surface temperature and
the sensor detection temperature have the temperature difference of
5.1.degree. C. at the maximum. As shown in FIG. 4C, the sensor
detection temperature has the changing rate of 0.8.degree. C./sec,
and the evaporator surface temperature and the sensor detection
temperature have the temperature difference of 5.2.degree. C. at
the maximum.
[0054] In FIGS. 5A-5C, air taken into the evaporator has a
relatively high load, and a voltage applied to the blower 8 is
different. As shown in FIG. 5A, the sensor detection temperature
has the changing rate of 0.4.degree. C./sec, and the evaporator
surface temperature and the sensor detection temperature have the
temperature difference of 1.5.degree. C. at the maximum. As shown
in FIG. 5B, the sensor detection temperature has the changing rate
of 0.7.degree. C./sec, and the evaporator surface temperature and
the sensor detection temperature have the temperature difference of
3.5.degree. C. at the maximum. As shown in FIG. 5C, the sensor
detection temperature has the changing rate of 0.7.degree. C./sec,
and the evaporator surface temperature and the sensor detection
temperature have the temperature difference of 4.2.degree. C. at
the maximum.
[0055] Due to the response delay, the sensor detection temperature
becomes higher than the evaporator surface temperature by about
5.degree. C. at the maximum. Further, if the evaporator surface
temperature is equal to or larger than -2.degree. C., the freezing
of the evaporator 9 is not generated while the compressor 11 is
controlled on and off. Therefore, if the compressor 11 is turned
off when the sensor detection temperature is equal to or larger
than 3.degree. C. (5.degree. C.-2.degree. C.), the freezing of the
evaporator 9 can be reduced, while the freezing of the evaporator 9
is easily generated when the evaporator 9 has a high cooling
speed.
[0056] Further, based on the nine conditions shown in FIGS. 3A-5C,
when the changing rate of the sensor detection temperature is equal
to or larger than 0.5.degree. C./sec, the freezing of the
evaporator 9 is generated in the area A, B, C. Therefore, a
marginal (limit) speed for the freezing of the evaporator 9 is
defined as 0.5.degree. C./sec. Furthermore, the evaporator surface
temperature is further decreased while the changing rate of the
evaporator surface temperature is measured. Therefore, a
temperature for turning off the compressor 11 is set to have
allowance of about 1.degree. C./sec. Thus, determination for
turning off the compressor 11 is to be performed when the sensor
detection temperature is smaller than 4.degree. C. (3.degree.
C.+1.degree. C.).
[0057] Next, control of the compressor 11 to reduce the freezing of
the evaporator 9 in advance will be described with reference to
FIG. 6. When the air-conditioning switch 27e is turned on, the ECU
28 determines that a sensor detection temperature TE detected by
the evaporator temperature sensor 26a is smaller than a first
predetermined temperature R1 (e.g., 4.degree. C.) or not (S100).
The ECU 28 repeats S100 until the ECU 28 determines that the sensor
detection temperature TE is smaller than the first predetermined
temperature R1. After the ECU 28 determines that the sensor
detection temperature TE is smaller than the first predetermined
temperature R1, the ECU 28 determines that the changing rate of the
sensor detection temperature TE is equal to or larger than a second
predetermined value R2 or not (S110). Here, as an example, the ECU
28 determines that a temperature change between adjacent sampling
timings is equal to or larger than 0.6.degree. C./sec or not
(TE(n-1)-TE(n).gtoreq.0.6).
[0058] When the ECU 28 determines that the changing rate of the
sensor detection temperature TE is smaller than the second
predetermined value R2 at S110, the ECU 28 determines that the
freezing of the evaporator 9 is not generated, and performs default
(ordinary) control of the compressor 11 (S170). The default control
is performed based on a control characteristic map shown of S170 in
FIG. 6. The sensor detection temperature TE is applied in the map
as a temperature TEO. When the compressor 11 is operating, the
compressor 11 is turned off at the temperature TEO. When the
compressor 11 is not operating, the compressor 11 is turned on at a
predetermined temperature (TEO+1.degree. C.), which is 1.degree. C.
higher than the temperature TEO. The control characteristic map is
stored in the ECU 28 in advance.
[0059] Here, the sensor detection temperature TE is smaller than
4.degree. C., so that the compressor 11 is turned on when the
sensor detection temperature TE is smaller than 5.degree. C.
(4.degree. C.+1.degree. C.). Thus, when the ECU 28 detects that the
sensor detection temperature TE is equal to or larger than the
predetermined temperature (TEO+1.degree. C.), the ECU 28 performs
the default control to turn on the compressor 11, in accordance
with the map of S170.
[0060] When the ECU 28 determines that the changing rate of the
sensor detection temperature TE is equal to or larger than the
second predetermined value (0.6.degree. C./sec) at S110, the ECU 28
turns off the compressor 11 (S120). This is because the cooling
speed of the evaporator 9 is so fast that the freezing of the
evaporator 9 may be generated. That is, the ECU 28 determines that
the freezing of the evaporator 9 will be generated. Thereby, a flow
of refrigerant is stopped in the refrigeration cycle device 10, so
that the evaporator surface temperature will be increased. Then,
the ECU 28 determines that the sensor detection temperature TE is
equal to or larger than a third predetermined temperature R3 (e.g.,
5.degree. C.) or not (S130). The third predetermined temperature R3
is higher than the predetermined temperature (TEO+1.degree.
C.).
[0061] The ECU 28 repeats S130 and keeps the compressor 11 off,
until when the ECU 28 determines that the sensor detection
temperature TE is equal to or larger than the third predetermined
temperature R3. When the ECU 28 determines that the sensor
detection temperature TE is equal to or larger than the third
predetermined temperature R3, the ECU 28 turns on the compressor 11
(S140). This is because the freezing of the evaporator 9 can be
avoided, and the ECU 28 determines that the temperature of the
evaporator 9 is increased, so that the evaporator 9 is needed to be
cooled. Thus, the ECU 28 continuously performs S100-S170 while the
air-conditioner is operating.
[0062] The sensor detection temperature is either the evaporator
surface temperature detected by the evaporator temperature sensor
26a, or the temperature of air at the downstream side of the
evaporator 9, which is detected by the evaporator downstream
temperature sensor (not shown). In either case, the sensor
detection temperature has the above-described response delay
relative to the evaporator surface temperature, which is actually
fluctuating. The ECU 28 controls the compressor 11 in consideration
of the response delay.
[0063] According to the first embodiment, in a case where the
compressor 11 is in stop state, when the evaporator surface
temperature or the temperature of air at the downstream side of the
evaporator 9 is equal to or larger than the predetermined
temperature (TEO+1.degree. C.), the ECU 28 turns on the compressor
11. When the changing rate of the evaporator surface temperature or
the changing rate of the temperature of air at the downstream side
of the evaporator 9 is equal to or larger than the second
predetermined value (0.6.degree. C./sec), the ECU 28 turns off the
compressor 11. Then, when the evaporator surface temperature or the
temperature of air at the downstream side of the evaporator 9
becomes equal to or larger than the third predetermined temperature
R3 (5.degree. C.), which is larger than the predetermined
temperature (TEO+1.degree. C.), the ECU 28 turns on (restarts) the
compressor 11.
[0064] Thus, possibility of the freezing of the evaporator 9 can be
predictable in advance, while the evaporator 9 is cooled and the
temperature of the evaporator 9 is decreased. Therefore, this
feed-forward control can effectively reduce the freezing of the
evaporator 9.
[0065] Further, by increasing the evaporator surface temperature or
the temperature of air at the downstream side of the evaporator 9
to turn on the compressor 11, control capable of reducing the
freezing of the evaporator 9 can be provided. Therefore, a
temperature of air blown into the vehicle compartment can be
restricted from increasing, and odorous component can be restricted
from flowing into the vehicle compartment. Thus, air blown into the
vehicle compartment can provide better feeling to an occupant, and
operation time of the refrigeration cycle device 10 can be reduced
so that power saving effect can be enhanced.
Second Embodiment
[0066] A control of the compressor 11 in a second embodiment will
be described with reference to FIGS. 7 and 8. When the
air-conditioning switch 27e is turned on, the ECU 28 performs a
subroutine A shown in FIG. 8 (S150 in FIG. 7).
[0067] As shown in FIG. 8, in the subroutine A, the ECU 28 performs
a treatment for detecting a revolution number Ne(rpm) of the
vehicle engine (S151). Next, when the detected revolution number Ne
is equal to or larger than a predetermined value N1, the ECU 28
applies the detected revolution number Ne into a control
characteristic map of S152, and calculates an evaporator surface
temperature TEOA. The predetermined value N1 is a revolution number
capable of causing the freezing of the evaporator 9, because the
compressor 11 has a high capacity for compressing refrigerant. The
predetermined value N1 is determined based on experiments, and
memorized in the ECU 28 in advance.
[0068] When the detected revolution number Ne is between N1 and N2,
the evaporator surface temperature TEOA is interpolated between
1.degree. C. and 4.degree. C. When the detected revolution number
Ne is equal to or larger than N2, the evaporator surface
temperature TEOA is constant (4.degree. C.). The control
characteristic map is stored in the ECU 28 in advance.
[0069] The treatment for detecting that the revolution number Ne is
equal to or larger than the predetermined value N1 is performed at
least while the evaporator 9 is cooled toward the lowest
temperature state. Thereafter, the treatment detects and predicts a
condition for generating the freezing of the evaporator 9. When the
condition for generating the freezing of the evaporator 9 is
detected, the evaporator surface temperature TEOA is calculated
based on the control characteristic map of S152. Thereby, a
reference evaporator surface temperature for turning on the
compressor 11 is further increased.
[0070] Next, the ECU 28 applies the evaporator surface temperature
TEOA calculated in the subroutine A into the temperature TEO of a
control characteristic map of S153 in FIG. 7. When the evaporator
surface temperature detected by the evaporator temperature sensor
26a is equal to the evaporator surface temperature TEOA, the
compressor 11 is turned off. When the evaporator surface
temperature detected by the evaporator temperature sensor 26a is
equal to a temperature 1.degree. C. higher than the evaporator
surface temperature TEOA, the compressor 11 is turned on. Thus, the
compressor 11 is continuously controlled. The ECU 28 repeats this
series of the feed-forward control to prevent the freezing of the
evaporator 9 while the air-conditioning switch 27e is on.
[0071] The evaporator surface temperature detected by the
evaporator temperature sensor 26a is used as the reference
evaporator surface temperature for turning on the compressor 11.
Alternatively, a temperature of air at the downstream side of the
evaporator 9 may be used as the reference evaporator surface
temperature. In this case, the temperature of air at the downstream
side of the evaporator 9 is processed by the subroutine A, and the
reference evaporator surface temperature is determined, similarly
to the evaporator surface temperature.
[0072] According to the second embodiment, while the evaporator 9
is cooled toward the lowest temperature state, the ECU 28 detects
the condition predicting the freezing of the evaporator 9. When the
condition is detected, the reference evaporator surface temperature
or the reference temperature of air at the downstream side of the
evaporator 9 for turning on the compressor 11 is increased, so that
the compressor 11 is continuously controlled.
[0073] Thus, the ECU 28 can perform the feed-forward control to
prevent the freezing of the evaporator 9 in advance. By increasing
the temperature of air at the downstream side of the evaporator 9
to turn on the compressor 11, air blown into the vehicle
compartment can provide better feeling to the occupant, and
operation time of the refrigeration cycle device 10 can be reduced
so that power saving effect can be enhanced.
[0074] Further, when the ECU 28 detects that the revolution number
Ne of the engine is equal to or larger than the predetermined value
N1, the ECU 28 calculates to increase the evaporator surface
temperature or the temperature of air at the downstream side of the
evaporator 9 based on the detected revolution number. The
calculated evaporator surface temperature or the calculated
temperature of air at the downstream side of the evaporator 9 is
used for turning on the compressor 11. When the revolution number
Ne of the engine is equal to or larger than predetermined value N1,
the compressor 11 has a high capacity for compressing refrigerant,
and the freezing of the evaporator 9 can be easily generated.
[0075] Thus, the freezing of the evaporator 9 can be predictable by
detecting that the revolution number Ne of the engine is equal to
or larger than the predetermined value N1, because the compressor
11 has the high capacity for compressing refrigerant. Further, the
freezing of the evaporator 9 can be effectively reduced, because
the evaporator surface temperature or the temperature of air at the
downstream side of the evaporator 9 calculated based on the
capacity for compressing refrigerant is used for turning on the
compressor 11.
[0076] Other parts in the second embodiment will be made similar to
the first embodiment.
Third Embodiment
[0077] A control of the compressor 11 in a third embodiment will be
described with reference to FIGS. 9 and 10. When the
air-conditioning switch 27e is turned on, the ECU 28 performs a
subroutine B shown in FIG. 10 (S154 in FIG. 9).
[0078] As shown in FIG. 10, in the subroutine B, the ECU 28
performs a treatment for detecting an outside air temperature
TAM(.degree. C.) through the outside air temperature sensor 26b
(S155). Next, when the detected outside air temperature TAM is
equal to or smaller than a predetermined value T2, the ECU 28
applies the detected outside air temperature TAM into a control
characteristic map of S156, and calculates an evaporator surface
temperature TEOB. The predetermined value T2 is an outside air
temperature capable of causing the freezing of the evaporator 9,
because the condenser 12 has a high cooling capacity. The
predetermined value T2 is determined based on experiments, and
memorized in the ECU 28 in advance.
[0079] When the detected outside air temperature TAM is between T1
and T2, the evaporator surface temperature TEOB is interpolated
between 1.degree. C. and 4.degree. C. When the detected outside air
temperature TAM is equal to or smaller than T1, the evaporator
surface temperature TEOB is constant (4.degree. C.). The control
characteristic map is stored in the ECU 28 in advance.
[0080] The treatment for detecting that the outside air temperature
TAM is equal to or smaller than the predetermined value T2 is
performed at least while the evaporator 9 is cooled toward the
lowest temperature state. Thereafter, the treatment detects and
predicts a condition for generating the freezing of the evaporator
9. When the condition for generating the freezing of the evaporator
9 is detected, the evaporator surface temperature TEOB is
calculated based on the control characteristic map of S156.
Thereby, a reference evaporator surface temperature for turning on
the compressor 11 is further increased.
[0081] Next, the ECU 28 applies the evaporator surface temperature
TEOB calculated in the subroutine B into the temperature TEO of a
control characteristic map of S157 in FIG. 9. When the evaporator
surface temperature detected by the evaporator temperature sensor
26a is equal to the evaporator surface temperature TEOB, the
compressor 11 is turned off. When the evaporator surface
temperature detected by the evaporator temperature sensor 26a is
equal to a temperature 1.degree. C. higher than the evaporator
surface temperature TEOB, the compressor 11 is turned on. Thus, the
compressor 11 is continuously controlled. The ECU 28 repeats this
series of the feed-forward control to prevent the freezing of the
evaporator 9 while the air-conditioning switch 27e is on.
[0082] The evaporator surface temperature detected by the
evaporator temperature sensor 26a is used as the reference
evaporator surface temperature for turning on the compressor 11.
Alternatively, a temperature of air at the downstream side of the
evaporator 9 may be used as the reference evaporator surface
temperature. In this case, the temperature of air at the downstream
side of the evaporator 9 is processed by the subroutine B, and the
reference evaporator surface temperature is determined, similarly
to the evaporator surface temperature.
[0083] According to the third embodiment, when the ECU 28 detects
that outside air temperature TAM outside of the vehicle compartment
is equal to or smaller than the predetermined value N2, the ECU 28
calculates to increase the evaporator surface temperature or the
temperature of air at the downstream side of the evaporator 9 based
on the detected outside air temperature. The calculated evaporator
surface temperature or the calculated temperature of air at the
downstream side of the evaporator 9 is used for turning on the
compressor 11. When the outside air temperature TAM is equal to or
smaller than predetermined value T2, the condenser 12 has a high
cooling capacity, and the freezing of the evaporator 9 can be
easily generated.
[0084] Thus, the freezing of the evaporator 9 can be predictable by
detecting that the outside air temperature TAM is equal to or
smaller than the predetermined value T2, because the condenser 12
has the high cooling capacity. Further, the freezing of the
evaporator 9 can be effectively reduced, because the evaporator
surface temperature or the temperature of air at the downstream
side of the evaporator 9 calculated based on the outside air
temperature TAM is used for turning on the compressor 11.
[0085] Other parts in the third embodiment will be made similar to
the first embodiment.
Fourth Embodiment
[0086] A control of the compressor 11 in a fourth embodiment will
be described with reference to FIGS. 11 and 12. When the
air-conditioning switch 27e is turned on, the ECU 28 performs a
subroutine C shown in FIG. 12 (S158 in FIG. 11).
[0087] As shown in FIG. 12, in the subroutine C, the ECU 28
performs a treatment for detecting a voltage Vb(V) applied to the
blower 8 for sending air toward the evaporator 9 (S159). Next, when
the detected voltage Vb is equal to or smaller than a predetermined
value V2, the ECU 28 applies the detected voltage Vb into a control
characteristic map of S160, and calculates an evaporator surface
temperature TEOC. The predetermined value V2 is a voltage capable
of causing the freezing of the evaporator 9, because the evaporator
9 has a high cooling speed. The predetermined value V2 is
determined based on experiments, and memorized in the ECU 28 in
advance.
[0088] When the detected voltage Vb is between V1 and V2, the
evaporator surface temperature TEOC is interpolated between
1.degree. C. and 4.degree. C. When the detected voltage Vb is equal
to or smaller than V1, the evaporator surface temperature TEOC is
constant (4.degree. C.). The control characteristic map is stored
in the ECU 28 in advance.
[0089] The treatment for detecting that the voltage Vb is equal to
or smaller than the predetermined value V2 is performed at least
while the evaporator 9 is cooled toward the lowest temperature
state. Thereafter, the treatment detects and predicts a condition
for generating the freezing of the evaporator 9. When the condition
for generating the freezing of the evaporator 9 is detected, the
evaporator surface temperature TEOC is calculated based on the
control characteristic map of S160. Thereby, a reference evaporator
surface temperature for turning on the compressor 11 is further
increased.
[0090] Next, the ECU 28 applies the evaporator surface temperature
TEOC calculated in the subroutine C into the temperature TEO of a
control characteristic map of S161 in FIG. 11. When the evaporator
surface temperature detected by the evaporator temperature sensor
26a is equal to the evaporator surface temperature TEOC, the
compressor 11 is turned off. When the evaporator surface
temperature detected by the evaporator temperature sensor 26a is
equal to a temperature 1.degree. C. higher than the evaporator
surface temperature TEOC, the compressor 11 is turned on. Thus, the
compressor 11 is continuously controlled. The ECU 28 repeats this
series of the feed-forward control to prevent the freezing of the
evaporator 9 while the air-conditioning switch 27e is on.
[0091] The evaporator surface temperature detected by the
evaporator temperature sensor 26a is used as the reference
evaporator surface temperature for turning on the compressor 11.
Alternatively, a temperature of air at the downstream side of the
evaporator 9 may be used as the reference evaporator surface
temperature. In this case, the temperature of air at the downstream
side of the evaporator 9 is processed by the subroutine C, and the
reference evaporator surface temperature is determined, similarly
to the evaporator surface temperature.
[0092] According to the fourth embodiment, when the ECU 28 detects
that the voltage Vb applied to the blower 8 is equal to or smaller
than the predetermined value V2, the ECU 28 calculates to increase
the evaporator surface temperature or the temperature of air at the
downstream side of the evaporator 9 based on the detected voltage.
The calculated evaporator surface temperature or the calculated
temperature of air at the downstream side of the evaporator 9 is
used for turning on the compressor 11. When the detected voltage is
equal to or smaller than predetermined value V2, the evaporator 9
has a high cooling speed, and the freezing of the evaporator 9 can
be easily generated.
[0093] Thus, the freezing of the evaporator 9 can be predictable by
detecting that the voltage Vb applied to the blower 8 is equal to
or smaller than the predetermined value V2, because the evaporator
9 has the high cooling speed. Further, the freezing of the
evaporator 9 can be effectively reduced, because the evaporator
surface temperature or the temperature of air at the downstream
side of the evaporator 9 calculated based on the voltage Vb applied
to the blower 8 is used for turning on the compressor 11.
[0094] Other parts in the fourth embodiment will be made similar to
the first embodiment.
Fifth Embodiment
[0095] A control of the compressor 11 in a fifth embodiment will be
described with reference to FIGS. 13, 8, 10 and 12. As shown in
FIG. 13, the subroutine A of the second embodiment, the subroutine
B of the third embodiment and the subroutine C of the fourth
embodiment are performed in the fifth embodiment. Thereafter, a
maximum temperature among the evaporator surface temperatures
calculated in the subroutines A, B, C is determined at S162, and
the maximum temperature is used in S163.
[0096] The subroutines A, B, C may be processed in any order. For
example, the subroutines A, B, C may be processed parallel to each
other. Further, only any two of the subroutines A, B, C may be
performed.
[0097] The subroutine A detects a condition, in which the
revolution number Ne of the vehicle engine is equal to or larger
than the predetermined value N1. The subroutine B detects a
condition, in which the outside air temperature TAM is equal to or
smaller than T2. The subroutine C detects a condition, in which the
voltage Vb applied to the blower 8 for sending air to the
evaporator 9 is equal to or smaller than the predetermined value
V2. When the ECU 28 detects at least one of the conditions, the
freezing of the evaporator 9 is determined to be easily
generated.
[0098] In this case, the conditions are monitored. When at least
one of the conditions is detected, the compressor 11 is turned on
at the increased evaporator surface temperature or the increased
temperature of air at the downstream side of the evaporator 9.
Therefore, accuracy for reducing the freezing of the evaporator 9
due to the feed-forward control can be enhanced.
[0099] Further, when the ECU 28 detects at least two of the
conditions, the ECU 28 calculates each of the evaporator surface
temperature and the temperature of air at the downstream side of
the evaporator 9 based on the detected conditions. A higher
temperature between the calculated evaporator surface temperature
and the calculated temperature of air at the downstream side of the
evaporator 9 can be used for turning on the compressor 11.
[0100] In this case, because the compressor 11 can be turned on at
the higher temperature, the freezing of the evaporator 9 can be
more effectively prevented in advance. Further, operation time of
the refrigeration cycle device 10 can be reduced so that power
saving effect can be more enhanced.
[0101] Further, when the ECU 28 detects at least two of the
conditions, the ECU 28 calculates to increase each of the
evaporator surface temperature and the temperature of air at the
downstream side of the evaporator 9 based on the detected
conditions. The higher temperature between the calculated
evaporator surface temperature and the calculated temperature of
air at the downstream side of the evaporator 9 can be used for
turning on the compressor 11.
[0102] Thus, the plural conditions, in which the freezing of the
evaporator 9 can be easily generated, can be detected. By using the
calculated higher temperature to control the compressor 11, the
freezing of the evaporator 9 can be more effectively prevented.
[0103] Other parts in the fifth embodiment will be made similar to
the first embodiment.
Other Embodiments
[0104] The capacity-variable compressor is used as the compressor
11 in the above embodiments. Alternatively, a capacity-fixed
compressor may be used as the compressor 11.
[0105] Further, when the revolution number Ne of the vehicle engine
is not used as a parameter to detect a condition for causing the
freezing of the evaporator 9, an electric compressor using battery
power may be used as the compressor 11.
[0106] Such changes and modifications are to be understood as being
within the scope of the present invention as defined by the
appended claims.
* * * * *